1. Field of Invention
The present invention relates to a reflector capable of reflecting light uniformly and enhancing brightness. Particularly, the invention pertains to a light diffusion reflector, which can be used in liquid crystal displays.
2. Description of the Prior Art
It is important to utilize a backlight source as an essential element for the displaying function and the brightness source of liquid crystal displays (LCDS) for enhancing the displaying brightness of the LCDs. Before the present invention, many methods associated with the modifications of the backlight source for improving the displaying brightness of LCDs have been proposed. For example, it has been proposed to improve the displaying brightness by increasing the number of the lamps and/or increasing the power of the lamps. Nevertheless, this approach would suffer the drawbacks associated with bulkiness and electricity-wasting problems.
An excellent reflector can enhance the brightness entirely, without narrowing the viewing angle. According to a real test, if the reflectivity of a module increases by 3-5%, the brightness of the same module at the same conditions will increase by 8-10%.
Moreover, the LCD product has been expanded from LCDs in laptop computers or LCD screens to LCD TVs. Thus, critical factors to be considered are sufficient imaging luminance, broad viewing angle, sharp image contrast, and desired service life. In order to meet the requirements, a direct type backlight has become the mainstream technology used in large LCD TVs. FIG. 1 is a schematic view of a direct type backlight module.
Though the direct type backlight module product usually provides a high luminance, bright and dark stripes easily occur due to the increase in the number of the lamps, and thereby the uniformity of light is influenced. In addition, the surface of a general reflector is planar, and when the incidence angle of light deviates from the normal, the reflected light will also deviate from the normal, thereby resulting in insufficient front-face brightness.
One approach to overcome the above drawbacks is to utilize a light diffusion plate. For example, JP 2000-11886 discloses etching metal on the surface of a glass substrate so as to obtain a reflector having a textured and convex-concave surface. In order to avoid the contact of the back surface of the glass substrate with the etching solution, the glass substrate should be protected, which renders the manufacturing process more complex and increases the difficulty in post-treating the etching solution.
Moreover, it has also been proposed to form a film having a convex-concave structure on the metal with a photosensitive resin by a mask lithography technique, so as to form a diffusion reflection film. However, the manufacturing process involving mask lithography is more expensive and not easy to be controlled.
After a wide range of research, it has been found that the above drawbacks can be overcome by directly applying a convex-concave structured film onto the surface of a reflector. Such a manufacturing process is simple and easy to be controlled, and may enhance the adhesion to the substrate.